The first real Panasonic GH4 competitor is the Sony A7s. And today Sony unveiled the pricing which is $2499 at Amazon. So let’s just take a short look about the advantages and disadvantages of each camera:
Sony A7s advantages:
Super clean High ISO. ISO range goes up to 409,600.
Full Frame look (that for some people is an advantage).
Big pixels likely means Higher Dynamic range and Color fidelity.
Superior Stills Image Quality (but with a bit less Megapixels)
Panasonic GH4 advantages:
4K recording on SD cards (A7s needs an external 4K recorder and can record XAVC-s 50Mbit/s at best)
10 bit output (A7s has 8bit output)
Autofocus is much faster (A7s autofocus pretty much sucks)
More available native lenses and cheaper. A7 system only has five (mostly expensive) FE lenses right now.
Powerzoom lenses (A7s has one on roadmap but price and release still have to be defined).
Actually it’s $2900 cheaper if you want 4K because the A7s “forces” you to buy the Atomos Shogun (here at BHphoto)
Let me know if I forgot to mention som major differences. But so far it looks like that overall the GH4 has the edge. I am sure at photokina we will get more and likely also cheaper 4K cameras. And we have to see by then if Panasonic managed to sell plenty of GH4 cameras…